Detect Scroll Up & Scroll down in ListView

Question

I have the following requirement:

• At first, data for page no: 2 is fetched from the server & the items are populated in a ListView.

Considering that both the prev page & next page are available in a scenario, the following code has been added:

 if(prevPageNo > 0){
    mListViewActual.setOnScrollListener(this);
 }

 if(nextPageNo > 0){
    mListViewActual.setOnScrollListener(this);
 }

What conditions should I put to detect scroll up & scroll down on the following methods:

1. void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount)
2. void onScrollStateChanged(AbsListView view, int scrollState)

After the action: scroll up & scroll down is detected , accordingly a service will be called with either the prev page no or next page no , to fetch the items to be populated in the Listview.

Any inputs will be helpful.

Gone through the following links but its not returning the correct scroll up / scroll down action:

link 1 link 2

Answer 1

this is a simple implementation:

lv.setOnScrollListener(new OnScrollListener() {
        private int mLastFirstVisibleItem;

        @Override
        public void onScrollStateChanged(AbsListView view, int scrollState) {

        }

        @Override
        public void onScroll(AbsListView view, int firstVisibleItem,
                int visibleItemCount, int totalItemCount) {

            if(mLastFirstVisibleItem<firstVisibleItem)
            {
                Log.i("SCROLLING DOWN","TRUE");
            }
            if(mLastFirstVisibleItem>firstVisibleItem)
            {
                Log.i("SCROLLING UP","TRUE");
            }
            mLastFirstVisibleItem=firstVisibleItem;

        }
    });

and if you need more precision, you can use this custom ListView class:

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.widget.AbsListView;
import android.widget.ListView;

/**
 * Created by root on 26/05/15.
 */
public class ScrollInterfacedListView extends ListView {


    private OnScrollListener onScrollListener;
    private OnDetectScrollListener onDetectScrollListener;

    public ScrollInterfacedListView(Context context) {
        super(context);
        onCreate(context, null, null);
    }

    public ScrollInterfacedListView(Context context, AttributeSet attrs) {
        super(context, attrs);
        onCreate(context, attrs, null);
    }

    public ScrollInterfacedListView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        onCreate(context, attrs, defStyle);
    }

    @SuppressWarnings("UnusedParameters")
    private void onCreate(Context context, AttributeSet attrs, Integer defStyle) {
        setListeners();
    }

    private void setListeners() {
        super.setOnScrollListener(new OnScrollListener() {

            private int oldTop;
            private int oldFirstVisibleItem;

            @Override
            public void onScrollStateChanged(AbsListView view, int scrollState) {
                if (onScrollListener != null) {
                    onScrollListener.onScrollStateChanged(view, scrollState);
                }
            }

            @Override
            public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
                if (onScrollListener != null) {
                    onScrollListener.onScroll(view, firstVisibleItem, visibleItemCount, totalItemCount);
                }

                if (onDetectScrollListener != null) {
                    onDetectedListScroll(view, firstVisibleItem);
                }
            }

            private void onDetectedListScroll(AbsListView absListView, int firstVisibleItem) {
                View view = absListView.getChildAt(0);
                int top = (view == null) ? 0 : view.getTop();

                if (firstVisibleItem == oldFirstVisibleItem) {
                    if (top > oldTop) {
                        onDetectScrollListener.onUpScrolling();
                    } else if (top < oldTop) {
                        onDetectScrollListener.onDownScrolling();
                    }
                } else {
                    if (firstVisibleItem < oldFirstVisibleItem) {
                        onDetectScrollListener.onUpScrolling();
                    } else {
                        onDetectScrollListener.onDownScrolling();
                    }
                }

                oldTop = top;
                oldFirstVisibleItem = firstVisibleItem;
            }
        });
    }

    @Override
    public void setOnScrollListener(OnScrollListener onScrollListener) {
        this.onScrollListener = onScrollListener;
    }

    public void setOnDetectScrollListener(OnDetectScrollListener onDetectScrollListener) {
        this.onDetectScrollListener = onDetectScrollListener;
    }


    public interface OnDetectScrollListener {

        void onUpScrolling();

        void onDownScrolling();
    }

}

an example for use: (don't forget to add it as an Xml Tag in your layout.xml)

scrollInterfacedListView.setOnDetectScrollListener(new ScrollInterfacedListView.OnDetectScrollListener() {
            @Override
            public void onUpScrolling() {
               //Do your thing
            }

            @Override
            public void onDownScrolling() {

             //Do your thing
            }
        });

Answer 2

Here is a working modified version from some of the above-indicated solutions.

Add another class ListView:

package com.example.view;

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.widget.AbsListView;

public class ListView extends android.widget.ListView {

    private OnScrollListener onScrollListener;
    private OnDetectScrollListener onDetectScrollListener;

    public ListView(Context context) {
        super(context);
        onCreate(context, null, null);
    }

    public ListView(Context context, AttributeSet attrs) {
        super(context, attrs);
        onCreate(context, attrs, null);
    }

    public ListView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        onCreate(context, attrs, defStyle);
    }

    @SuppressWarnings("UnusedParameters")
    private void onCreate(Context context, AttributeSet attrs, Integer defStyle) {
        setListeners();
    }

    private void setListeners() {
        super.setOnScrollListener(new OnScrollListener() {

            private int oldTop;
            private int oldFirstVisibleItem;

            @Override
            public void onScrollStateChanged(AbsListView view, int scrollState) {
                if (onScrollListener != null) {
                    onScrollListener.onScrollStateChanged(view, scrollState);
                }
            }

            @Override
            public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
                if (onScrollListener != null) {
                    onScrollListener.onScroll(view, firstVisibleItem, visibleItemCount, totalItemCount);
                }

                if (onDetectScrollListener != null) {
                    onDetectedListScroll(view, firstVisibleItem);
                }
            }

            private void onDetectedListScroll(AbsListView absListView, int firstVisibleItem) {
                View view = absListView.getChildAt(0);
                int top = (view == null) ? 0 : view.getTop();

                if (firstVisibleItem == oldFirstVisibleItem) {
                    if (top > oldTop) {
                        onDetectScrollListener.onUpScrolling();
                    } else if (top < oldTop) {
                        onDetectScrollListener.onDownScrolling();
                    }
                } else {
                    if (firstVisibleItem < oldFirstVisibleItem) {
                        onDetectScrollListener.onUpScrolling();
                    } else {
                        onDetectScrollListener.onDownScrolling();
                    }
                }

                oldTop = top;
                oldFirstVisibleItem = firstVisibleItem;
            }
        });
    }

    @Override
    public void setOnScrollListener(OnScrollListener onScrollListener) {
        this.onScrollListener = onScrollListener;
    }

    public void setOnDetectScrollListener(OnDetectScrollListener onDetectScrollListener) {
        this.onDetectScrollListener = onDetectScrollListener;
    }
}

And an interface:

public interface OnDetectScrollListener {

    void onUpScrolling();

    void onDownScrolling();
}

And finally how to use:

com.example.view.ListView listView = (com.example.view.ListView) findViewById(R.id.list);
listView.setOnDetectScrollListener(new OnDetectScrollListener() {
    @Override
    public void onUpScrolling() {
        /* do something */
    }

    @Override
    public void onDownScrolling() {
        /* do something */
    }
});

In your XML layout:

<com.example.view.ListView
    android:id="@+id/list"
    android:layout_width="match_parent"
    android:layout_height="match_parent"/>

This is my first topic, do not judge me harshly. =)

Answer 3

Those methods cannot be used to detect scrolling directions directly. There are many ways of getting the direction. A simple code(untested) for one such method is explained below :

public class ScrollTrackingListView extends ListView {

    private boolean readyForMeasurement = false;
    private Boolean isScrollable = null;
    private float prevDistanceToEnd = -1.0;
    private ScrollDirectionListener listener = null;

    public ScrollTrackingListView(Context context) {
        super(context);
        init();
    }

    public ScrollTrackingListView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public ScrollTrackingListView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init();
    }

    private void init() {
        ViewTreeObserver observer = getViewTreeObserver();
        observer.addOnGlobalLayoutListener(globalLayoutListener);
        setOnScrollListener(scrollListener);
    }

    private ViewTreeObserver.OnGlobalLayoutListener globalLayoutListener
            = new ViewTreeObserver.OnGlobalLayoutListener() {

        @Override
        public void onGlobalLayout() {
            readyForMeasurement = true;
            calculateDistanceToEnd();
        }

    };

    public void registerScrollDirectionListener(ScrollDirectionListener listener) {
        scrollDirectionListener = listener;
    }

    public void unregisterScrollDirectionListener() {
        scrollDirectionListener = null;
    }

    private OnScrollListener scrollListener
            = new OnScrollListener() {

        @Override
        public void onScrollStateChanged(AbsListView absListView, int i) {
            calculateDistanceToEnd();
        }

        @Override
        public void onScroll(AbsListView absListView, int i, int i1, int i2) {
            // Do nothing
        }

    };

    private void calculateDistanceToEnd() {

        if (readyForMeasurement) {

            // I'm using the height of the layout, horizontal scrollbar and
            // content along with scroll down offset

            // computeVerticalScrollExtent is used to compute the length of the thumb within the scrollbar's track.
            // The length of the thumb is a function of the view height and the content length.
            int verticalScrollExtent = computeVerticalScrollExtent();
            int verticalScrollOffset = computeVerticalScrollOffset();
            int verticalScrollRange = computeVerticalScrollRange();
            int horizontalScrollBarHeight = getHorizontalScrollbarHeight();

            /**
             * 1. Let "R" represent the range of the vertical scrollbar. This corresponds to the length of the content
             * in the view.
             * 2. Let "E" represent the extent of the vertical scrollbar. The extent is a constant value and is
             * (probably) equal to a value proportional to the height of the view.
             * 3. Offset "o" represents the current position in the range that is visible to the user. It can take
             * values from "0 to E".
             *
             * Now the DistanceToEnd is calculated using these three values as follows :
             *
             * DistanceToEnd = (R - o) / E
             *
             * DistanceToEnd will hold the value in NumberOfScreenToEnd units.
             *
             */

            float distanceToEnd =
                    ((float)(verticalScrollRange - verticalScrollOffset))/((float)(verticalScrollExtent));

            if(prevDistanceToEnd == -1) {
                 prevDistanceToEnd = distanceToEnd;
            } else {
                 if(listener != null) {
                     if(distanceToEnd > prevDistanceToEnd) {
                        // User is scrolling up
                         listener.onScrollingUp();
                     } else {
                        // User is scrolling up
                         listener.onScrollingDown();
                    }
                 }
                 prevDistanceToEnd = distanceToEnd;
            }

            if(isScrollable == null) {
                // Check if the view height is less than a screen (i.e., no scrolling is enabled)
                if((horizontalScrollBarHeight + verticalScrollExtent) >= verticalScrollRange) {
                    isScrollable = Boolean.FALSE;
                } else {
                    isScrollable = Boolean.TRUE;
                }
            }

        }

    }

    public interface ScrollDirectionListener {

        public void onScrollingUp();

        public void onScrollingDown();

    }

}

The idea is to calculate the distanceToEnd. If distanceToEnd increases, the user is scrolling up and if it decreases, the user is scrolling down. That will also give you the exact distance to the end of the list.

If you are just trying to know whether the user is scrolling up or down you can override the onInterceptTouchEvent to detect the scrolling direction like below :

    @Override
    public boolean onInterceptTouchEvent(MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                mInitialX = event.getX();
                mInitialY = event.getY();
                return true;
            case MotionEvent.ACTION_MOVE:
                final float x = event.getX();
                final float y = event.getY();
                final float yDiff = y - mInitialY; // yDiff less than 0.0 implies scrolling down while yDiff greater than 0.0 implies scrolling up. If I try to add the less than or greater than symbols, the preview refuses to display it.
                if(yDiff less than 0.0) listener.onScrollingDown();
                else if(yDiff greater than 0.0) listener.onScrollingUp();
                break;
        }
        return super.onInterceptTouchEvent(event);
    }

Answer 4

Simple way to detect scroll up/down on android listview

@Override
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount){
  if(prevVisibleItem != firstVisibleItem){
    if(prevVisibleItem < firstVisibleItem)
      //ScrollDown
    else
      //ScrollUp

  prevVisibleItem = firstVisibleItem;
}

dont forget

yourListView.setOnScrollListener(yourScrollListener);

Answer 5

Trick about detect scroll up or down in listview, you just call this function on onScroll function in OnScrollListener of ListView.

private int oldFirstVisibleItem = -1;
    private protected int oldTop = -1;
    // you can change this value (pixel)
    private static final int MAX_SCROLL_DIFF = 5;

    private void calculateListScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
        if (firstVisibleItem == oldFirstVisibleItem) {
            int top = view.getChildAt(0).getTop();
            // range between new top and old top must greater than MAX_SCROLL_DIFF
            if (top > oldTop && Math.abs(top - oldTop) > MAX_SCROLL_DIFF) {
                // scroll up
            } else if (top < oldTop && Math.abs(top - oldTop) > MAX_SCROLL_DIFF) {
                // scroll down
            }
            oldTop = top;
        } else {
            View child = view.getChildAt(0);
            if (child != null) {
                oldFirstVisibleItem = firstVisibleItem;
                oldTop = child.getTop();
            }
        }
    }

Answer 6

I have encountered problems using some example where the cell size of ListView is great. So I have found a solution to my problem which detects the slightest movement of your finger . I've simplified to the minimum possible and is as follows:

private int oldScrolly;


@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {

}

@Override
public void onScroll(AbsListView view, int firstVisibleItem, int    visibleItemCount, int totalItemCount) {

            View view = absListView.getChildAt(0);
            int scrolly = (view == null) ? 0 : -view.getTop() + absListView.getFirstVisiblePosition() * view.getHeight();
            int margin = 10;

            Log.e(TAG, "Scroll y: " + scrolly + " - Item: " + firstVisibleItem);


            if (scrolly > oldScrolly + margin) {
                Log.d(TAG, "SCROLL_UP");
                oldScrolly = scrolly;
            } else if (scrolly < oldScrolly - margin) {
                Log.d(TAG, "SCROLL_DOWN");
                oldScrolly = scrolly;
            }
        }
    });

PD: I use the MARGIN to not detect the scroll until you meet that margin . This avoids problems when I show or hide views and avoid blinking of them.